ST. LOUIS, July 17 (UPI) -- The physical health risks that accompany a smoking habit have been pretty well documented at this point. But new research suggests there may also be mental health consequences to smoking cigarettes.

In a survey analyzing anti-tobacco policy measures -- like raising taxes and instituting public smoking bans -- and rates of suicide in all 50 U.S. states between the years 1990 and 2004, researchers found a correlation. More aggressive anti-tobacco initiatives resulted in reduced rates of suicide.

"Our analysis showed that each dollar increase in cigarette taxes was associated with a 10-percent decrease in suicide risk," explained Richard Grucza, an epidemiologist at Washington University in St. Louis and the survey's lead author. "Indoor smoking bans also were associated with risk reductions."

As with all surveys, the findings show correlation, not causation. Researches suggest a range of causal mechanisms are at play. Previous research has shown correlations between psychiatric disorders and smoking. As well, smokers are more likely to abuse drugs and alcohol.

But studies have also suggested cigarettes affect the neural pathways that control the brain's pleasure centers.

"Nicotine is a plausible candidate for explaining the link between smoking and suicide risk," explained Grucza. "Like any other addicting drug, people start using nicotine to feel good, but eventually they need it to feel normal," he continued. "And as with other drugs, that chronic use can contribute to depression or anxiety, and that could help to explain the link to suicide."

Still, it's clear many other factors are at play. Suicide rates have risen steadily over the last decade in the United States, while rates of cigarette smoking have never been lower. Some 50 years ago, nearly half the country smoked cigarettes. Today, only about 18 percent light up.

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